This week, nine more US airports were given the go ahead to offer charter flights to Cuba, raising the total from three to 12.

There are still a number of restrictions preventing an American invasion: business travellersare required to obtain approval in advance from the US government and tourists are prohibited from spending money in Cuba. But by granting more airports the rights to charter flights, the US government is allowing airlines to lay the groundwork and infrastructure needed for full-on commercial service when the outdated travel ban is finally tossed into the dustbin of history.

This relaxation will greatly expand the number of religious and academic travellers to Cuba, which is undoubtedly why more airports have been given rights to offer charter flights there. (Though it will be interesting to see how rigorously travellers will be checked for their religious or academic credentials.)

"Last year, roughly 500,000 Americans visited Cuba - more than 90% of them Cuban-Americans visiting family members. This year, with a slight relaxation in US travel restrictions, that number likely will climb to at least 600,000," said Eason Jordan, CEO of the US-Cuba Business Bureau. "If US restrictions on American travelers went away altogether, probably 2,000,000 Americans would travel to Cuba in the first year... but lifting the travel restrictions altogether would take an act of Congress - highly unlikely for at least two years."

Once the ban is completely lifted and commercial flights are okayed, Delta Air Lines and American Airlines will be in the best position take advantage of the potentially huge US-to-Cuba market, because both have alliances with airlines already operating there. Delta's SkyTeam Alliance partner AirFrance (and soon, KLM) currently offers several nonstop flights between Havana and Amsterdam or Paris, making it easy for Delta to start operating flights as soon as the ban is lifted. AeroMexico, also a SkyTeam partner, offers flights to Cuba from several Mexican cities including Cancun and Mexico City. The same goes for American Airlines and its Oneworld partner, Iberia, which has deep ties in Havana and offers flights between Havana and Madrid.

Flying to Cuba from the US is not cheap. Jordan explained, "Flights to Cuba are relatively expensive because Cuban government fees are exceptionally high. So charter operators complain their margins are very small. A Miami-Havana roundtrip ticket costs roughly $500 even though the two cities are only 200 miles apart."